Evaluation of physiologic change in the trauma patient depends heavily upon intrusive techniques such as chronically placed catheters, magnetic flow probes, radioisotope injection, and dye dilution methods. Variables typically monitored in intensive care units are blood pressure, pulse, EKG and temperature. While considerable attention has been given to impedance and ultrasonic methods for noninvasive clinical determination of circulatory function, little work has been done to translate commercially used nuclear magnetic resonance flowmeter principles for biological investigation. This study is directed to the design of cylindrical nuclear magnetic resonance systems for monitoring blood flow in the limbs of trauma patients. Similar systems are being investigated for monitoring blood flow in the aorta, vena cava, liver and kidney. Preliminary studies in the isolated perfused kidney of the dog show that regional blood flow measurements can be done with nuclear magnetic resonance techniques. Furthermore, peripheral blood flow from the radial artery has been measured from the human using the single coil NMR system. A 12.5 centimeter internal diameter lumen device is currently being fabricated to measure peripheral blood flow in the limbs of the human adult. These systems will be integrated into a computerized patient monitoring system for non-invasive evaluation of the trauma patient.